.TH std::is_volatile 3 "2024.06.10" "http://cppreference.com" "C++ Standard Libary"
.SH NAME
std::is_volatile \- std::is_volatile

.SH Synopsis
   Defined in header <type_traits>
   template< class T >              \fI(since C++11)\fP
   struct is_volatile;

   std::is_volatile is a UnaryTypeTrait.

   If T is a volatile-qualified type (that is, volatile, or const volatile), provides
   the member constant value equal to true. For any other type, value is false.

   If the program adds specializations for std::is_volatile or std::is_volatile_v, the
   behavior is undefined.

.SH Template parameters

   T - a type to check

   Helper variable template

   template< class T >                                           \fI(since C++17)\fP
   inline constexpr bool is_volatile_v = is_volatile<T>::value;



Inherited from std::integral_constant

.SH Member constants

   value    true if T is a volatile-qualified type, false otherwise
   \fB[static]\fP \fI(public static member constant)\fP

.SH Member functions

   operator bool converts the object to bool, returns value
                 \fI(public member function)\fP
   operator()    returns value
   \fI(C++14)\fP       \fI(public member function)\fP

.SH Member types

   Type       Definition
   value_type bool
   type       std::integral_constant<bool, value>

.SH Possible implementation

   template<class T> struct is_volatile : std::false_type {};
   template<class T> struct is_volatile<volatile T> : std::true_type {};

.SH Example


// Run this code

 #include <type_traits>
 #include <valarray>

 static_assert(!std::is_volatile_v<int>);
 static_assert(std::is_volatile_v<volatile int>);
 static_assert(std::is_volatile_v<volatile const int>);
 static_assert(std::is_volatile_v<volatile std::valarray<float>>);
 static_assert(!std::is_volatile_v<std::valarray<volatile float>>);

 int main() {}

.SH See also

   is_const checks if a type is const-qualified
   \fI(C++11)\fP  \fI(class template)\fP
